With the recent size reduction and performance improvement of an information processing apparatus such as a communication device or a server, the heat value per volume of such apparatus is increasing. Thus, for some information processing apparatuses, the need to cool the air therein with cooling fans is increasing. However, as with any other electronic components, these cooling fans are not free of malfunctions. Occasionally, when a cooling fan of an information processing apparatus malfunctions, the cooling fan is changed while the apparatus is in operation.
FIG. 14 illustrates a redundant configuration of cooling fans according to a first related technique. According to this first related technique, a plurality of cooling fans 1011 and 1012 are arranged in a single holder 102 arranged on one side in a chassis 1001 of an information processing apparatus. Thus, according to the first related technique, when any one of the cooling fans 1011 and 1012 malfunctions, an operator extracts the holder 102 through the front face of the chassis 1001 of the information processing apparatus in the direction of an arrow 103 and changes the malfunctioning one of the cooling fans 1011 and 1012.
In FIG. 14, the cooling fans 1011 and 1012 are fixed in the single holder 102. Thus, even when only one of the cooling fans 1011 and 1012 malfunctions, both the cooling fans 1011 and 1012 held in the holder 102 are extracted.
Normally, it takes at least a few minutes from extraction of a malfunctioning cooling fan 101 to installation of a new cooling fan. Thus, a certain volume of air flow for radiation needs to be ensured during change of a cooling fan. However, the first related technique fails to ensure such air flow. Namely, when the operator is changing a malfunctioning one of the cooling fans 1011 and 1012 and installing the holder 102 into the chassis 1001, the temperature in the chassis 1001 is increased. As a result, abnormal operations may be brought about in the information processing apparatus.
FIG. 15 illustrates a redundant configuration of cooling fans according to a second related technique. According to this second related technique, holders 1121 and 1122 are arranged on the near and far sides, respectively, on one side in the chassis 1002 of an information processing apparatus. The holders 1121 and 1122 accommodate cooling fans 1111 and 1112, respectively.
Thus, for example, when the cooling fan 1111 malfunctions, the operator extracts only the holder 1121 accommodating the cooling fan 1111 in the direction of an arrow 103 through the front side of the chassis 1002 of the information processing apparatus. The operator then changes the cooling fan 1111 accommodated in the holder 1121. During the change, the other holder 1122 remains at the original position in the chassis 1002 of the information processing apparatus. Thus, until the operator completes changing the cooling fan 1111, the cooling fan 1112 can execute a minimum air-cooling operation.
When the cooling fan 1112 malfunctions, the operator extracts only the holder 1122 accommodating the cooling fan 1112 in the direction of an arrow 113 through the rear side of the chassis 1002 of the information processing apparatus. During the change, the holder 1121 remains at the original position in the chassis 1001 of the information processing apparatus. Thus, until the operator completes changing the cooling fan 1112, the cooling fan 1111 can execute a minimum air-cooling operation.
FIG. 16 illustrates a redundant configuration of cooling fans according to a third related technique. According to this third related technique, holders 1221 and 1222 are arranged on both sides in a chassis 1003 of an information processing apparatus. One holder 1221 accommodates cooling fans 12111 and 12112, and the other holder 1222 accommodates cooling fans 12121 and 12122.
According to this third related technique, if the cooling fan(s) 12111 and/or 12112 accommodated in the holder 1221 malfunction(s), the operator extracts only the holder 1221 accommodating the cooling fans 12111 and 12112 in the direction of an arrow 1031 through the front side of the chassis 1003 of the information processing apparatus. The operator then changes the malfunctioning cooling fan(s) 12111 and/or 12112. During the change, the other holder 1222 remains at the original position in the chassis 1003 of the information processing apparatus. Thus, until the operator completes changing the cooling fan(s) 12111 and/or 12112, the cooling fan 12121 and 12122 can execute a minimum air-cooling operation in the chassis 1003.
Likewise, according to this third related technique, if the cooling fan(s) 12121 and/or 12122 accommodated in the holder 1222 malfunction(s), the operator extracts only the holder 1222 accommodating the cooling fans 12121 and 12122 in the direction of an arrow 1032 through the front side of the chassis 1003 of the information processing apparatus. The operator then changes the malfunctioning cooling fan(s) 12121 and/or 12122. During the change, the other holder 1221 remains at the original position in the chassis 1003 of the information processing apparatus. Thus, until the operator completes changing the cooling fan(s) 12121 and/or 12122 the cooling fan 12111 and 12112 can execute a minimum air-cooling operation in the chassis 1003.
Many information processing apparatuses such as servers are particularly required to have availability, that is, low fault incidence and high restoration speed in case of failure. Thus, even when one of the cooling fans malfunctions and needs to be changed, until the malfunctioning cooling fan is changed, a certain volume of air flow for radiation needs to be ensured by the other cooling fan(s). In this sense, since the second and third related techniques adopt a redundant configuration of cooling fans, even when the operator is changing a malfunctioning cooling fan, a minimum volume of air flow can be ensured. In practice, the operator changes cooling fans while checking for any abnormalities sequentially according to a procedure.
Thus, unlike the information processing apparatus adopting the first related technique, based on the information processing apparatuses adopting the second and third related techniques, a minimum volume of air flow can be ensured during change of a cooling fan. However, the second and third related techniques involve the following problems.
First, in the case of the second related technique, when changing the cooling fans 1111 and 1112, the operator needs to extract the two holders 1121 and 1122 in the two directions of the arrows 103 and 113 through the front and rear sides of the chassis 1002, respectively. Thus, the degree of installation freedom in the information processing apparatus is decreased. In recent years, installation density in information processing apparatuses is increasing, and in many cases, the operator can extract components only through the front or back side of the information processing apparatus. Thus, a decrease in the degree of installation freedom is a major obstacle to the introduction of information processing apparatuses.
In the case of the third related technique, the operator can extract the two holders 1221 and 1222 in the same direction. However, according to the third related technique, the holders 1221 and 1222 are arranged on the right and left sides in the chassis 1003, respectively. Thus, assuming that the total volume of the two holders 1221 and 1222 is equal to that of the two holders 1121 and 1122 according to the second related technique, the length of each of the cooling fans 12111, 12112, 12121, and 12122 in the direction of the rotating shaft thereof is half the length of the cooling fans 1111 and 1112 in the corresponding direction.
Normally, if a cooling fan, which is installed on one side in a chassis and used in a pull manner, is compared with two cooling fans, which have a width half that of the above cooling fan, are installed on both sides in a chassis, and are used in a push-pull manner, the latter two cooling fans generate a smaller volume of air flow. To equalize the volumes of air flow between the above two cases, it is necessary to provide a larger power to the latter two cooling fans. Namely, use of the third related technique causes a problem of decreasing cooling efficiency during a normal operation.
To solve the above problems, as a fourth related technique, for example, Patent Document 1 discloses an apparatus including a sleeve that is slightly smaller than an opening portion of the chassis. A cooling fan holder that can be freely inserted into or extracted from the sleeve is arranged. According to this fourth related technique, when the operator pulls the holder accommodating a plurality of cooling fans from the chassis, the sleeve is also pulled. The holder is pulled within a range in which the holder does not fall out of this sleeve.
The holder includes cells each accommodating a cooling fan as a unit. The operator pulls the holder from the sleeve to a limit position, and among these units, the operator lifts up an arbitrary unit to be changed. In this way, the operator can change a malfunctioning cooling fan. While changing a cooling fan, the operator can allow the other cooling fans to operate. Thus, because of this sleeve, the air in the chassis can be cooled as normal.
[Patent Document 1]
    Japanese Patent Kokai Publication No. JP2009-117629A (paragraphs 0043 to 0046 and FIGS. 3, 4, and 7)